Not applicable.
Not applicable.
The present invention relates to chemical delivery systems, and in particular to an apparatus for delivering high-purity or ultra-high purity chemicals to a use point, such as a semiconductor fabrication facility or tool(s) for chemical vapor deposition. Although the invention may have other applications, it is particularly applicable in semiconductor fabrication.
Semiconductor manufacturers require chemicals having at least a high-purity for production processes to avoid defects in the fabrication of semiconductor devices. The chemicals used in the fabrication of integrated circuits usually must have an ultra-high purity to allow satisfactory process yields. As integrated circuits have decreased in size, there has been an increase in the need to maintain the purity of source chemicals.
One ultra-high purity chemical used in the fabrication of integrated circuits is tetrakis(dimethylamido)titanium (TDMAT). TDMAT is used widely in integrated circuit manufacturing operations such as chemical vapor deposition (CVD) to form titanium and titanium nitride films, vias and barrier layers.
Integrated circuit fabricators typically require TDMAT with 99.99+% purity, preferably 99.999999+%(8-9""s+%) purity. This high degree of purity is necessary to maintain satisfactory process yields. It also necessitates the use of special equipment to contain and deliver the high-purity or ultra-high purity TDMAT to CVD reaction chambers.
High-purity chemicals and ultra-high purity chemicals, such as TDMAT, are delivered from a bulk chemical delivery system to a use point, such as a semiconductor fabrication facility or tool(s). A delivery system for high-purity chemicals is disclosed in U.S. Pat. No. 5,465,766 (Seigele, et al.). (Related patents include U.S. Pat. Nos. 5,562,132; 5,590,695; 5,607,002; 5,711,354; 5,878,793 and 5,964,254.) The system comprises: a bulk canister located in a remote chemical cabinet with a delivery manifold/purge panel; a refillable stainless steel ampoule to supply high-purity source chemicals to an end user; and a control unit to supervise and control the refill operation and to monitor the level of the bulk container. The system has two basic modes of operation: (1) a normal process operation during which high-purity source chemical is supplied to the end user; and (2) the refill mode of operation during which the refillable stainless steel ampoule is refilled with high-purity chemical.
Solvent purging systems for removal of low vapor pressure chemicals from process conduits are disclosed in U.S. Pat. Nos. 5,964,230 and 6,138,691. Such systems add additional complexity to purging and increase the amount of materials which must be disposed of.
Low dead space couplings are known, such as U.S. Pat. No. 6,161,875.
TDMAT is considered a low vapor pressure, high purity chemical by the semiconductor industry, and thus presents special problems when breaking a process line or changing out a process container where the line must be cleaned prior to such detachment. Significant time delays in cleaning down a line or conduit are a disadvantage in the throughput of a wafer processing facility, where expensive tools and large batch processing of expensive wafers, each containing hundreds of integrated circuits require fast processing and avoidance of significant or lengthy offline time for cleaning or changeout of process containers or vessels.
The Present Invention is more specifically directed to the field of process chemical delivery in the electronics industry and other applications requiring low vapor pressure, high purity chemical delivery. More specifically, the present invention is directed to apparatus and processes for the cleaning of process chemical delivery lines, containers and associated apparatus, particularly during changeout of process chemical or process chemical containers in such process chemical delivery lines, quickly and thoroughly, but without the added complexity of solvent purge systems, when processing with low vapor pressure, high purity chemicals.
Evacuation and gas purge of process chemical lines has been used to remove residual chemicals from delivery lines. Both vacuum draw and inert gas purge are successful in quickly removing high volatility chemicals, but are not effective with low volatility chemicals. Safety is a problem when extracting highly toxic materials.
Use of solvents to remove residual chemicals has been suggested to remove low vapor pressure chemicals from process lines when the lines need to be disconnected such as for replacement of a vessel or container for either refill or maintenance. However, solvent systems are complex and require a source of solvent and a means to handle the contaminated solvent after it has been used for its cleaning function.
The present invention overcomes the drawbacks of the prior art in purging and cleaning chemical process lines for low vapor pressure chemicals without the requirements of lengthy purge cycles of pressurized gas and vacuum or the complexity of solvent systems, as will be more fully set forth below.
The present invention is a purgeable manifold for transfer of low vapor pressure high purity chemicals in a high purity chemical delivery system, comprising; (a) a first conduit for detachably connecting a first vessel for containing the high purity chemical to a second vessel of high purity chemical, a source of pressurized gas and a source of vacuum; (b) a first block valve assembly having first and second diaphragm valves, each diaphragm valve having a diaphragm and having a valve seat side and a diaphragm side, wherein the valve seat side of each diaphragm valve is juxtaposed to the other valve seat side of the other diaphragm valve, and each valve seat side of each diaphragm valve having high purity chemical flow communication with the first conduit; (c) a first low dead space connector in the first conduit for detaching the conduit from the first vessel; (d) a second conduit, for delivering low vapor pressure, high purity chemicals to the first vessel, the second conduit connected to the diaphragm side of the first diaphragm valve; and (e) a third conduit, for communicating in a sequenced manner, pressurized gas and vacuum to the first conduit, connected to the diaphragm side of the second diaphragm valve.
More preferably, the present invention is a high purity chemical delivery system for refilling a vessel for low vapor pressure, high purity chemical and delivering the chemical to a process tool that uses the chemical, comprising: (a) a vessel for containing a low vapor pressure, high purity chemical; (b) a purgeable manifold for transfer of low vapor pressure high purity chemicals from a source of high purity chemical refill to the vessel, the manifold comprising; (i) a heated first conduit for detachably connecting the vessel to the source of high purity chemical refill, a source of pressurized gas and a source of vacuum; (ii) a heated first block valve assembly having first and second diaphragm valves, each diaphragm valve having a diaphragm and having a valve seat side and a diaphragm side, the diaphragm comprising a flexible disc having a convex side toward the diaphragm side of the valves and a concave side toward the valve seat side of the valve, wherein the valve seat side of each diaphragm valve is juxtaposed to the other valve seat side of the other diaphragm valve, and each valve seat side of each diaphragm valve, having high purity chemical flow communication with the first conduit, each diaphragm valve has a pneumatic valve actuator operatively engaged to the convex side of the diaphragm to actuate an open and closed condition of the diaphragm valves; (iii) a first low dead space connector in the first conduit for detaching the conduit from the vessel; (iv) a second conduit, for delivering low vapor pressure, high purity chemicals to the vessel, the second conduit connected to the diaphragm side of the first diaphragm valve; (v) a third conduit, for communicating in a sequenced manner, pressurized gas and vacuum to the first conduit, connected to the diaphragm side of the second diaphragm valve; (c) a source of pressurized gas; (d) a source of vacuum; and (e) a second block valve assembly having third and fourth diaphragm valves, each diaphragm valve having a diaphragm and having a valve seat side and a diaphragm side, wherein the valve seat side of each diaphragm valve is juxtaposed to the other valve seat side of the other diaphragm valve, each valve seat side of each diaphragm valve having flow communication with the third conduit, the third diaphragm valve connected to a source of pressurized gas through the diaphragm side of the third diaphragm valve, and the fourth diaphragm valve connected to a source of vacuum through the diaphragm side of the fourth diaphragm valve.